Long acting sustained-release formulation containing dopamine receptor agonist and the preparation method thereof

ABSTRACT

The present invention relates to a long-acting sustained-release dosage form for treatment of Parkinson Disease, comprising a dopamine receptor agonist and a pharmaceutically acceptable biodegradable polymer accessories, wherein the content of the dopamine receptor agonist in the sustained-release dosage form is 5-50% by weight, and the content of the pharmaceutically acceptable polymer accessories is 50-95% by weight.

TECHNICAL FIELD

The present invention relates to long-acting sustained-release dosageforms of dopamine receptor agonists, in particular to injectablesustained-release microspheres, implants and injectable gels ofdopaminic drugs and methods for preparing them, and to methods of usingthese compounds for the manufacture of long-acting sustained releasepharmaceuticals, especially microspheres, for the treatment oradjunctive therapy of dopamine receptor associated diseases, and for thetreatment of Parkinsonic diseases such as Parkinson's disease orParkinson's syndrome (hereinafter called as Parkinson Disease).

BACKGROUND ART

Dopamine receptor agonists are important agents for the treatment ofParkinson Disease. At present, clinically used dopamine receptoragonists include dopaminic agonists such as rotigotine, pramipexole,ropinirole, pergolide, terguride, quinagolide, cabergoline and theirderivatives and pharmaceutically acceptable salts, and those underclinical trails include sumanirole, SLV-308, adrogolide, ABT-431,Dinapsoline, BAM-1110 and their derivatives and pharmaceuticallyacceptable salts.

The above medicines usually are administrated orally or transdermally inclinic. Although the oral administration is convenient, patients underadvanced Parkinson Disease usually have failure of memory and may forgetto take medicines, which will deteriorate their conditions. In addition,the relatively great fluctuation of drug concentration after oraladministration may aggravate side-effects and result in “on-offphenomenon”, and gastrointestinal tract and liver first pass effectreduce the bioavailability. For example, the bioavailability ofrotigotine for oral administration is only 1-5% due to the first passeffect in liver, so that oral dosage forms are not suitable. On theother hand, the transdermal absorption of normal transdermal dosageforms such as ointments, plasters, etc. is not sufficient and oftenvaries because the transdermal absorption is affected by many factors.In addition, transdermal dosage forms are affected by low permeabilityof skin and thus have low intake, low bioavailability and greatindividual difference, so that their therapeutic effects are limited,especially for advanced Parkinson Disease patients.

Parenteral administration such as injection can avoid first pass effect,but rotigotine and pramipexole, etc. have a short half-life of only acouple of hours and thus should be administrated several times per day,and other drugs with a relatively longer half-life still should beadministrated daily or bidaily and hardly facilitate the administrationfor patients with Parkinson Disease.

Thus, it is expected to provide a long-acting sustained-release dosageform of dopamine receptor agonist, which is preferably not orallyadministrated, but intramuscularly injected or subcutaneouslyadministrated, and which can maintain a stable release rate for severalweeks, several months or longer so as to reduce as much as possible thepain of patients with Parkinson Disease.

CN1531428A (WO2002/015903) disclosed a Depot-form type sustained-releasepreparation of rotigotine, wherein the use of a so-called “depot”obtained by suspending rotigotine hydrochloride in an oilly solventextended the administration interval to more than one day. AlthoughCN1531428A cites the prior art EP0625069 (CN1090172A) which mentionedthe preparation of microparticles or micro-capsules (i.e., themicrospheres of the present invention) of rotigotine for theimplementation of sustained-release, it discloses nothing about thecomponents of micro-capsules or sustained-release microspheres ofrotigotine and proportions thereof.

To achieve a long-acting sustained-release preparation that have aadministration interval of once weekly or bi-weekly, even once monthlyor longer, not only the sustained-release dosage form should stablyrelease drug in vivo for a long period in order to maintain an effectiveblood drug level in vivo during the period, but also the dosage formshould not cause significant side-effects after it is injected into thebody, Thus, the use and amounts of both the active component andaccessories should be strictly defined in order to implement theadministration interval of one or more weeks, even one month and toachieve better therapeutic effects.

CN1531428A and CN1090172A disclose nothing about the sustained-releasedosage forms of dopamine receptor agonists and accessories thereof, sothat long-acting sustained-release dosage forms (having anadministration interval of one or two weeks, even one month or more) ofdopamine receptor agonists including rotigotine are actually stillunknown.

The inventors of the present invention conducted deep researches forimplementation of the long-acting sustained-release of dopamine receptoragonists, and discovered that injectable sustained-release microspheres,implants and injectable gels obtained by using a biodegradable polymerto embed an active component could continuously, stably release theactive component for several weeks even several months after they areadministrated intramuscularly or subcutaneously, and in the meantimethey had high bioavailability, small fluctuation of blood drug level andgreatly reduced administration frequency. As compared with traditionaloral dosage forms, the side-effects were reduced, the frequency ofoccurrence of “on-off phenomena” decreased, in the meantime thebioavailability increased significantly, the compliance of patients wereimproved, and the therapeutic effects of these medicines were achievedto the fullest extent. On this basis, the present invention is carriedout.

DISCLOSURES OF THE INVENTION

The object of the present invention is to provide a long-actingsustained-release dosage form of dopamine receptor agonist, such asinjectable microspheres, injectable gels and implants, etc. According tothe present invention, the administration interval is extended from oneday or less to one week, two weeks, one month, two months or more, sothat the administration frequency decreases significantly, the firstpass effect is avoided, the bioavailability and therapeutic effects areenhanced, and thereby the pain of patients with Parkinson Disease isalleviated remarkably and their life quality is improved.

The above object of the present invention is carried out by thefollowing technical solutions.

The present invention is to provide a long-acting sustained-releasedosage form, such as injectable microspheres, injectable gels, implants,etc., especially injectable microspheres, of dopamine receptor agonist,especially rotigotine.

The present invention further provides a method for treatment ofParkinson Disease by using a long-acting sustained-release dosage form.

Concretely, the present invention relates to a long-actingsustained-release dosage form for treatment of Parkinson Diseasecomprising an effective amount of dopamine receptor agonist and apharmaceutically acceptable biodegradable polymer accessories, whereinthe weight content of the dopamine receptor agonist in thesustained-release dosage form is 5-50%, and the weight content of thepharmaceutically acceptable polymer accessories in the sustained-releasedosage form is 50-95%.

The dopamine receptor agonist is one selected from rotigotine,pramipexole, ropinirole, pergolide, cabergoline, terguride, quinagolide,sumanirole, SLV-308, adrogolide (ABT-431), Dinapsoline and BAM-1110 andtheir derivatives or pharmaceutically acceptable salts, or a combinationof two or more of them.

The pharmaceutically acceptable biodegradable polymer accessories is oneselected from poly(lactide-glycolide), polylactic acid, polyglycolicacid, poly(3-hydroxy-butyrate), polylactone, polyanhydride,poly(hydroxy-butyrate)-co-(hydroxy-valerate), polypropylene-glucose,poly(lactic acid)-polyglycol, and poly(hydroxyacetic acid)-polyglycol,or a combination of two or more of them.

The long-acting sustained release dosage form of the above dopaminereceptor agonist is preferably injectable microspheres, injectable gels,implants, etc.

The above dopamine receptor agonist in the sustained release dosage formis preferably present in the form of solid solution.

In the above long-acting sustained-release dosage form, thepharmaceutically acceptable biodegrade polymer accessories is selectedpreferably from poly(lactide-glycolide), polylactic acid,polycaprolactone, and polyanhydride,poly(hydroxy-butyrate)-co-(hydroxy-valerate), or a combination of two ormore of them, more preferably from poly(lactide-glycolide), polylacticacid, and polyanhydride, or a combination of two or more of them,particularly more preferably poly(lactide-glycolide), more particularlya poly(lactide-glycolide) having a molecular weight of 5,000-100,000dalton.

In the above poly(lactide-glycolide), the polymerization ratio oflactide to glycolide is between 95:5 and 5:95, preferably between 75:25and 25:75.

Among the dopamine receptor agonists, their pharmaceutically acceptablesalts are salts formed between pharmaceutically active components andinorganic, acids, organic acids or acidic amino acids, wherein theinorganic acids are hydrochloric acid, sulfuric acid, phosphoric acid ornitric acid; the organic acids are citric acid, fumaric acid, maleicacid, acetic acid, benzoic acid, methane sulfonic acid, naphtholsulfonic acid, or p-toluene sulfonic acid; and the acidic amino acid isglutamic acid or aspartic acid, etc.

More concretely, pramipexole or its derivative or pharmaceuticallyacceptable salt is the free base of pramipexole or pramipexoledihydrochloride, etc.; ropinirole or its derivative or pharmaceuticallyacceptable salt is the free base of ropinirole or ropinirolehydrochloride, etc.; pergolide or its derivative or pharmaceuticallyacceptable salt is the free base of pergolide or pergolidemethanesulfonate, etc.; cabergoline or its derivative orpharmaceutically acceptable salt is the free base of cabergoline orcabergoline diphosphonate, etc.; terguride or its derivative orpharmaceutically acceptable salt is the free base of terguride orterguride maleate, etc.; quinagolide or its derivative orpharmaceutically acceptable salt is the free base of quinagolide orquinagolide hydrochloride, etc.; sumanirole or its derivative orpharmaceutically acceptable salt is the free base of sumanirole orsumanirole maleate, etc.; SLV-308 or its derivative or pharmaceuticallyacceptable salt is the free base of SLV-308 or SLV-308 hydrochloride,etc.; adrogolide (ABT-431) or its derivative or pharmaceuticallyacceptable salt is the adrogolide, adrogolide hydrochloride ortransformant A-86929 thereof, etc.; Dinapsoline or its derivative orpharmaceutically acceptable salt is the Dinapsoline or Dinapsolinehydrobromide, etc.; and BAM-1110 or its derivative or pharmaceuticallyacceptable salt is the BAM-1110 or BAM-1110 maleate, etc.

Among the above dopamine receptor agonists, the most preferable one isrotigotine as shown in the general formula (Ia) and its derivatives orpharmaceutically acceptable salts:

wherein R₁ represents hydrogen atom, C₁-C₁₀ alkylacyl or arylacyl(preferably hydrogen atom, C₂-C₄ alkylacyl or arylacyl); R₂ representshydrogen atom, C₁-C₁₀ alkyl, preferably C₂-C₄ alkyl; X represents carbonatom or nitrogen atom or oxygen atom or sulfur atom; n is an integerselected from 1 to 10 (preferably 1 to 3); the pharmaceuticallyacceptable salts are formed between the free base of rotigotine andhydrochloric acid, acetic acid, phosphoric acid, sulfuric acid, lacticacid or citric acid. The preferable rotigotine type compounds arerotigotine acetate, rotigotine benzoate, rotigotine propionate,rotigotine butyrate and rotigotine iso-butyrate and hydrochloridesthereof.

In the above long-acting sustained-release dosage form, the weightcontent of dopamine receptor agonist is preferably from 10% to 40%, andthe weight content of the pharmaceutically acceptable polymeraccessories is from 60% to 90%; and the weight ratio of the dopaminereceptor agonist to the pharmaceutically acceptable polymer accessoriesis (10-30):(90-70).

When the above long-acting sustained-release dosage form is injectablesustained-release microspheres, its particle diameter is preferablybetween 50 and 200 micrometers. The other contents and merits of thepresent invent are further illustrated in the following details.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the differential thermal analysis diagram of rotigotinemicrospheres with different contents.

FIG. 2 is the particle diameter distribution diagram of thesustained-release microspheres obtained in Example 1.

FIG. 3 is the scanning electron microscope photo of thesustained-release microspheres obtained in Example 1.

FIG. 4 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example 1in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and a represents accumulative release.

FIG. 5 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example 2in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 6 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example 3in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 7 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example 4in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 8 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example 5in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 9 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example 6in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 10 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example11 in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 11 is the polygonal diagram of daily release rate and accumulativerelease rate of the sustained-release microspheres obtained in Example13 in a simulative release liquid having a pH value of 7.4, wherein □represents daily release, and  represents accumulative release.

FIG. 12 is the polygonal diagram of blood rotigotine concentrationchange in vivo test (beagle) for the microspheres obtained in Example 3.

FIG. 13 is the diagram of comparison between the polygonal diagram ofdaily or accumulative release rate in pH7.4 simulative release liquidand the polygonal diagram of blood rotigotine concentration change invivo test (beagle) for the sustained-release microspheres obtained inExample 3, wherein □ represents daily release, and  representsaccumulative release.

FIG. 14 is the polygonal diagram of daily release rate and accumulativerelease rate of the implant obtained in Example 20, wherein □ representsdaily release, and  represents accumulative release.

FIG. 15 is the polygonal diagram of daily release rate and accumulativerelease rate of the injectable gel obtained in Example 22, wherein □represents daily release, and  represents accumulative release.

FIG. 16 is the polygonal diagram of daily release rate and accumulativerelease rate of the rotigotine microspheres (actually containing 7.8% ofactive component) obtained in Example 24 in a simulative release liquidhaving a pH value of 7.4, wherein □ represents daily release, and represents accumulative release.

FIG. 17 is the polygonal diagram of blood rotigotine concentrationchange in vivo test (beagle) for the rotigotine microspheres obtained inExample 24.

FIG. 18 is the polygonal diagram of daily release rate and accumulativerelease rate of the rotigotine microspheres (actually containing 26.5%of active component) obtained in Example 25 in a simulative releaseliquid having a pH value of 7.4, wherein □ represents daily release, and represents accumulative release.

FIG. 19 is the polygonal diagram of daily release rate and accumulativerelease rate of the rotigotine microspheres (actually containing 34% ofactive component) obtained in Example 26 in a simulative release liquidhaving a pH value of 7.4, wherein □ represents daily release, and represents accumulative release.

FIG. 20 is the polygonal diagram of blood rotigotine concentrationchange in vivo test (beagle) for the rotigotine microspheres obtained inExample 26.

FIG. 21 is the polygonal diagram of daily release rate and accumulativerelease rate of the rotigotine microspheres (actually containing 41% ofactive component) obtained in Example 27 in a simulative release liquidhaving a pH value of 7.4, wherein □ represents daily release, and represents accumulative release.

FIG. 22 is the polygonal diagram of daily release rate and accumulativerelease rate of the rotigotine microspheres (actually containing 43% ofactive component) obtained in Example 28 in a simulative release liquidhaving a pH value of 7.4, wherein □ represents daily release, and represents accumulative release.

FIG. 23 is the polygonal diagram of daily release rate and accumulativerelease rate of the rotigotine microspheres (actually containing 47% ofactive component) obtained in Example 29 in a simulative release liquidhaving a pH value of 7.4, wherein □ represents daily release, and represents accumulative release.

BEST MODES FOR CARRYING OUT THE PRESENT INVENTION

The long-acting sustained-release dosage form of the present inventionfor treatment of Parkinson Disease comprises an effective amount ofdopamine receptor agonist and a proper amount of pharmaceuticallyacceptable biodegradable polymer accessories, and specific examplesinclude injectable sustained-release microspheres, injectable gels,implants, etc.

Obviously, besides the above main components (i.e., the dopaminereceptor agonist as active component, and the pharmaceuticallyacceptable polymer accessories), the sustained-release dosage form ofthe present invention may further comprise other components essentialfor preparation and administration of the dosage form, such as solvents,buffers, isotonizing agents, etc., which are not limited in the presentinvention. All mentioned proportions or contents concerning tosustained-release dosage form are based on the total amount of theactive component and the pharmaceutically acceptable polymeraccessories.

Wherein, the dopamine receptor agonist is one selected from rotigotine,pramipexole, ropinirole, pergolide, cabergoline, terguride, quinagolide,sumanirole, SLV-308, adrogolide (ABT-431), Dinapsoline and BAM-1110 andtheir derivatives or pharmaceutically acceptable salts, or a combinationof two or more of them.

The above mentioned pharmaceutically acceptable salts are salts formedbetween dopamine receptor inhibitors and pharmaceutically acceptableacids, specifically inorganic acids, organic acids or acidic aminoacids, wherein the inorganic acids are hydrochloric acid, sulfuric acid,phosphoric acid or nitric acid; the organic acids are citric acid,fumaric acid, maleic acid, acetic acid, benzoic acid, methane sulfonicacid, naphthol sulfonic acid, or p-toluene sulfonic acid; and the acidicamino acid is glutamic acid or aspartic acid, etc.

In the present invention, the pramipexole or its derivative orpharmaceutically acceptable salt is the relevant compounds as disclosedin EP186087 and U.S. Pat. No. 4,886,812 and other improved compounds orpharmaceutically acceptable salts as disclosed in other documents,preferably the free base of pramipexole or pramipexole dihydrochloride,etc.

Ropinirole or its derivative or pharmaceutically acceptable salt is therelevant compounds as disclosed in U.S. Pat. No. 4,452,808 or theropinirole derivatives or pharmaceutically acceptable salts thereof asdisclosed by other documents, preferably the free base of ropinirole orropinirole hydrochloride, etc.

Pergolide or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed in U.S. Pat. No.4,166,182 or the pergolide derivatives or pharmaceutically acceptablesalts thereof as disclosed by other documents, preferably the free baseof pergolide or pergolide methanesulfonate, etc.

Cabergoline or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed in U.S. Pat. No.4,526,892 and EP888243 or the cabergoline derivatives orpharmaceutically acceptable salts thereof as disclosed by otherdocuments, preferably the free base of cabergoline or cabergolinediphosphonate, etc.

Terguride or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed in U.S. Pat. No.3,953,454 and DE3001752 or the terguride derivatives or pharmaceuticallyacceptable salts thereof as disclosed by other documents, preferably thefree base of terguride or terguride maleate, etc.

Quinagolide or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed by U.S. Pat. No.4,565,818 and EP77754 or quinagolide derivatives or pharmaceuticallyacceptable salts thereof as disclosed by other documents, preferably thefree base of quinagolide or quinagolide hydrochloride, etc.

Sumanirole or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed in U.S. Pat. No.5,478,734 or the sumanirole derivatives or pharmaceutically acceptablesalts thereof as disclosed by other documents, preferably the free baseof sumanirole or sumanirole maleate, etc.

SLV-308 or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed in WO00/29397 orSLV-308 derivatives or pharmaceutically acceptable salts as disclosed byother documents, preferably the free base of SLV-308 or SLV-308hydrochloride, etc.

Adrogolide (ABT-431) or its derivative or pharmaceutically acceptablesalt is the selected from the relevant compounds as disclosed inWO9422858 or the adrogolide derivatives or pharmaceutically acceptablesalts thereof as disclosed by other documents, preferably the free baseof adrogolide, adrogolide hydrochloride or transformant A-86929 ofadrogolide, etc.

Dinapsoline or its derivative or pharmaceutically acceptable salt is theselected from the relevant compounds as disclosed in WO97/06799 orDinapsoline derivatives or pharmaceutically acceptable salts thereof asdisclosed by other documents, preferably the free base of Dinapsoline orDinapsoline hydrobromide, etc.

BAM-1110 or its derivative or pharmaceutically acceptable salt is therelevant compounds as disclosed in U.S. Pat. No. 4,713,457 or BAM-1110derivatives or pharmaceutically acceptable salts thereof as disclosed byother documents, preferably the free base of BAM-1110 or BAM-1110maleate, etc.

In the long-acting sustained-release dosage form of dopamine receptoragonist of the present invention, the active component is mostpreferably rotigotines, i.e., rotigotine compounds and derivatives orpharmaceutically acceptable salts thereof.

The structural formula of rotigotines is shown in the general formula(Ia):

wherein R₁ represents hydrogen atom, C₁-C₁₀ alkylacyl or arylacyl,preferably hydrogen atom, C₂-C₄ alkylacyl or arylacyl; R₂ representshydrogen atom, C₁-C₁₀ alkyl (preferably C₁-C₅ alkyl); X representscarbon atom or nitrogen atom or oxygen atom or sulfur atom; n is aninteger selected from 1 to 10, preferably 1 to 3, most preferably 2; thepharmaceutically acceptable salts thereof are formed between the freebase of rotigotine and hydrochloric acid, acetic acid, phosphoric acid,sulfuric acid, lactic acid or citric acid; the preferable rotigotinecompounds and derivatives thereof are preferably rotigotine, rotigotineacetate, rotigotine propionate, rotigotine benzoate, as well asrotigotine butyrate and rotigotine iso-butyrate and hydrochloridesthereof, specifically the compounds (I), (II), (III) or (IV) as shown inthe following table.

Ccompound R₁ R₂ X n I Hydrogen n-propyl S 2 II Acetyl n-propyl S 2 IIIPropionyl n-propyl S 2 IV Benzoyl n-propyl S 2 V Butyl n-propyl S 2 VIIso-butyl n-propyl S 2

If the compound (I) is used as mother nucleus of rotigotine fordenomination, the compounds (II)-(VI) are named as rotigotine acetate,rotigotine propionate, rotigotine benzoate, rotigotine butyrate androtigotine iso-butyrate. Among the above compounds, rotigotine is themost preferable one, i.e., the compound (I), and its pharmaceuticallyacceptable salt is rotigotine hydrochloride.

The active component in the long-acting sustained-release dosage form ofthe present invention may further be the metabolites or transformants(prodrugs) thereof, besides the above compounds.

The pharmaceutically acceptable polymer accessories of the presentinvention is selected from poly(lactide-glycolide), polylactic acid,polyglycolic acid, poly(3-hydroxy-butyrate), polylactone, polyanhydride,poly(hydroxy-butyrate)-co-(hydroxy-valerate), polypropylene-glucose,poly(lactic acid)-polyglycol, and poly(hydroxyacetic acid)-polyglycol,or a combination of two or more of them, wherein the molecular weightthereof is between 2,000 and 1,000,000 dalton, and the pharmaceuticallyacceptable polymer accessories of the present invention is preferablypoly(lactide-glycolide), polylactic acid, polycaprolactone,polyanhydride, poly(hydroxy-butyrate)-co-(hydroxy-valerate), or acombination of two or more of them.

When the sustained-release dosage form is injectable microspheres, thepharmaceutically acceptable polymer accessories of the present inventionis more preferably a poly(lactide-glycolide) having a molecular weightof 2,000-100,000 dalton, more preferably 5,000-50,000, wherein thepolymerization ratio of lactide to glycolide in thepoly(lactide-glycolide) is between 95:5 and 5:95, preferably between75:25 and 25:75, most preferably about 50:50.

When the sustained-release dosage form is injectable gels or implant,the pharmaceutically acceptable polymer of the present invention ispreferably polylactic acid) or polyanhydride having a molecular weightof between 2,000 and 1,000,000 dalton.

In the long-acting sustained-release dosage form of the presentinvention, the weight percentage content of the dopamine receptoragonist in the sustained-release dosage form is 5-50%, preferably10-50%, more preferably 10-40%, most preferably 10-30%; and the weightcontent of the pharmaceutically acceptable polymer accessories is50-95%, preferably 50-90%, more preferably 60-90%, most preferably70-90%.

If the weight content of the dopamine receptor agonist is less than 5%,the blood drug level cannot be maintained at a sufficiently high level;while if the weight content is higher than 50%, the release of drug maybe unstable and side effects may occur.

When the content of dopamine receptor agonist in the sustained-releasedosage form is at a certain level, this drug is homogeneouslydistributed in the pharmaceutically acceptable accessories and ispresent in a state of solid solution, which ensures the stable releaseof drug. On the contrary, if the content is relatively high, the drug isnot present in a state of solid solution in the dosage form, and thedrug release may be unstable. This is more important for thesustained-release microspheres, and it is deemed as an importantmechanism of causing sudden-release of drug that the drug is not presentin a state of solid solution in microspheres. As for othersustained-release dosage forms such as injectable gels or implants,since they do not flow with blood as microspheres and have lesspossibility to generate sudden-release, the content range may beproperly broadened, but should not exceed 50%.

This is further illustrated by taking rotigotine microspheres asexample. The differential thermal analysis spectra of rotigotinemicrospheres with different contents as made according to the method offollowing examples and rotigotine per se as control are shown in FIG. 1.In FIG. 1, the curve a is the differential thermal curve when therotigotine load is less than 30%, the curve b is the differentialthermal curve when the rotigotine load is 34%, the curve c is obtainedwhen the load is 47%, and the curve d is the differential thermal curveof rotigotine per se.

According to FIG. 1, rotigotine is a crystalline solid and has a meltingpoint of 79-80° C. (see the curve d). When the drug load is less than30% in microspheres, rotigotine has a good compatibility with thecopolymer of lactic acid and hydroxy-acetic acid, and rotigotine isessentially completely dissolved in the polymer carrier and forms asolid solution so that the melting point of rotigotine is not observed(see the curve a). However, when the drug load reaches to 34%, themelting point of rotigotine is observed at 73° C. (see the curve b) andrises with the increase of the drug load, for example, when the drugload is 47%, the melting point of rotigotine is 76° C. (see the curvec), and the heat absorption area increases as well, which means thatwhen the drug load is more than 34%, not all rotigotine is present insolid solution state, and a part of rotigotine becomes crystal, so thatthe microspheres are not of a homogeneous phase system and containseparated phases, while this kind of phase separation not only affectsthe physical and mechanical properties of the microspheres, but alsoresults in a higher initial release and a quicker sustained-release.

When the content of rotigotine is constant, the melting point and heatabsorption area of rotigotine in microspheres are lower or smaller thanthe melting point and heat absorption area of pure rotigotine (see thecurve d), because the rotigotine crystal in microspheres is not perfectand only a part of rotigotine is crystallized.

The present invention provides not only a long-acting sustained-releasedosage form containing one of the above pharmaceutical compounds assingle active component, but also a long-acting sustained-release dosageform containing two or more of the above pharmaceutical compounds incombination as active components as well as pharmaceutically acceptablepolymer accessories, which dosage form, such as long-actingsustained-release injectable microspheres, injectable gels or implants,has same or different sustained-release effects and implements thesynergistic effects of several different active components.

The long-acting sustained-release dosage forms of the present invention,such as injectable sustained-release microspheres, implants orinjectable gels, have an administration interval of at least one week,preferably at least two weeks, wherein the implants and gels have anadministration interval of at least one month. The injectablemicrospheres, implants and injectable gels of the present invention areseparated illustrated as follows.

Sustained-Release Microspheres

The sustained-release microspheres of dopamine receptor agonist of thepresent invention (also called as injectable microspheres, microspheresin the present invention) are prepared according to conventional methodsin the art.

The sustained-release injectable microspheres of dopamine receptoragonist of the present invention have a diameter preferably between 1and 250 micrometers, most preferably between 50 and 200 micrometers, soas to maintain a certain time-effect, biodegradability and to avoid theeffects on blood circulation, because microspheres with excessivelysmall diameter can hardly maintain pharmaceutical action for a long timeand may obstacle blood capillary and influence blood circulation, whilemicrospheres with excessively large diameter have a too slow initialrelease and cannot reach a therapeutically effective blood drug level.

For the sustained-release microspheres of the present invention, theload of active component should not be excessively low, otherwise theexcessively large amount of microspheres injected to patients may causeside-effects such as pain and so on; while if the load is excessivelyhigh, serious sudden-release and overdose may occur when themicrospheres are administrated to patients.

Specifically, the weight content of the active component is 5-50%,preferably 10-40%, most preferably 10-30%, and the weight content of thepharmaceutically acceptable degradable polymer accessories is 50-95%,preferably 60-90%, most preferably 70-90%.

According to the following examples and experiments, the blood druglevel cannot be maintained at a sufficiently high level when the weightcontent of dopamine receptor agonist is less than 5%; on the contrary,when the weight content is higher then 50%, the drug release isunstable, and sudden-release and side-effects may occur.

According to the following examples and experiments, the proper drugload should be not higher than 50%, preferably less than 30%. Accordingto the minimum blood drug level for therapy and the acceptable injectionamount of microspheres, the drug load is most preferably between 10% and30%.

In the long-acting sustained-release microspheres of the presentinvention, the dopamine receptor agonist is selected preferably fromrotigotine and derivatives or pharmaceutically acceptable salts thereof,wherein rotigotine and derivatives thereof are preferably rotigotine,rotigotine acetate, rotigotine propionate, rotigotine butyrate,rotigotine isobutyrate, and rotigotine benzoate, and theirpharmaceutically acceptable salts are preferably hydrochlorides.

In the injectable microspheres of rotigotine and derivatives orpharmaceutically acceptable salts thereof of the present invention,based on the total weight of rotigotine compound and pharmaceuticallyacceptable polymer accessories, rotigotine is 5-50%, preferably 10-50%,more preferably 10-40%, most preferably 10-30%, and the pharmaceuticallyacceptable polymer accessories is 50-95%, preferably 50-90%, morepreferably 60-90%, most preferably 70-90%.

When the microspheres of rotigotine and derivatives or pharmaceuticallyacceptable salts thereof of the present invention are prepared,rotigotine and derivatives or pharmaceutically acceptable salts shouldbe in solid solution state, i.e., the active component is not separatedfrom accessories and is present in homogeneous phase.

The microspheres of the present invention are prepared according toconventional methods for preparation of microspheres in the art, such asspray-drying method, solvent-volatilizing method, andatomizing-extracting method, but are not limited to these methods.

When solvent-volatilizing method is employed to prepare the microspheresof the present invention, dopamine receptor agonist and pharmaceuticallyacceptable biodegradable accessories are dissolved in an organic solventto form an organic phase. In addition, a pharmaceutically acceptablewater soluble polymer is used to form a continuous water phase. Theorganic phrase is injected through tubules into the continuous phase andsufficiently emulsified under vigorous agitation of mechanical stirringor ultrasonic wave to form microspheres, then the organic solvent isvolatized, and the formed microspheres are separated by filtration anddried. If necessary, the microspheres are further subjected toconventional post treatment such as water-washing and grading, dryingtreatment such as vacuum drying or freeze-drying, and subpackage.

During the above operations, the dopamine receptor agonist and thepharmaceutically acceptable biodegradable accessories are thoseaforementioned. In view of operation, the organic solvent should be asufficiently volatile, low-residual and low-boiling point organicsolvent, for example, dichloromethane, chloroform, ethyl acetate, ethylether, and mixture solvents of their combination, The pharmaceuticallyacceptable polymer used for forming the continuous water phase isselected from polyvinyl alcohol, sodium carboxymethylcellulose,polyvinyl pyrrolidone, sodium polymethacrylate, sodium polyacrylate, ora combination of two or more of them, but is not limited to these.

When the organic phase is prepared, the contents of dopamine receptoragonist and the pharmaceutically acceptable degradable accessories inthe organic solvent are not limited if they can be dissolved in theorganic solvent, but in view of the balance between possibleconcentration and viscosity and the reduction of organic solvent, theconcentration is preferably 1-30%(w/v). When polyvinyl alcohol, sodiumcarboxymethylcellulose, polyvinyl pyrrolidone, sodium polymethacrylate,sodium polyacrylate, or a combination of two or more of them is used forpreparing the continuous water phase, its concentration is notspecifically limited, but according to its solubility in water, itsconcentration in the water phase is preferably 0.01-12% (w/v), morepreferably 0.01-10.0% (w/v), more preferably 0.1-5% (w/v). When theorganic phase is injected into the water phase under vigorous agitationto form microspheres, the volume ratio of the organic phase to the waterphase is at a level so that the organic phase is sufficiently dispersedin the water phase to form microspheres with sufficiently small particlesize and homogeneousness. However, if too much water phase is used, thepost treatment is complex and the cost increases, so that in view ofthese aspects, the volume ratio of the organic phase to the water phaseis from about 1:4 to 1:100.

The microspheres can also be prepared by spray-drying method. When thesustained-release microspheres of dopamine receptor agonist are preparedby spray-drying method, the dopamine receptor agonist and thepharmaceutically acceptable biodegradable accessories are sufficientlydissolved in an organic solvent to form an organic solution, then thesolution is filtered and processed by a conventional spray-drying methodto form microspheres. If necessary, the microspheres are subjected toconventional post treatment such as water washing and grading, and thensubpackaged.

When the above spray-drying method is employed to prepare microspheres,the organic solvent can be dichloromethane, chloroform, ethyl acetate,dioxane, ethyl ether, acetone, tetrahydrofuran, glacial acetic acid, anda mixture solvent of them, but is not limited to these.

When the organic phase is prepared, the content of the pharmaceuticallyacceptable degradable accessories in the organic solvent is not limitedif these accessories can be dissolved in the organic solvent, but in aview of the balance between the possible concentration and the reductionof organic solvent, the concentration is preferably 1-30%(w/v).

The microspheres can also be prepared by employing anatomizing-extracting method. When the atomizing-extracting method isemployed to prepare the microspheres of dopamine receptor agonist, thedopamine receptor agonist and pharmaceutically acceptable biodegradablepolymer accessories are sufficiently dissolved in an organic solvent(which can dissolve the dopamine receptor agonist and thepharmaceutically acceptable biodegradable polymer accessories) to forman organic solution, then the organic solution is atomized into anorganic non-solvent (an organic solvent that cannot dissolve thedopamine receptor agonist and the pharmaceutically acceptablebiodegradable polymer accessories) or water, and microspheres areobtained by extracting. If necessary, the microspheres are furthersubjected to conventional post treatment such as water-washing andgrading, and then subpackaged.

When the microspheres are prepared according to the aboveatomizing-extracting method, the organic solvent is dichloromethane,chloroform, ethyl acetate, dioxane, ethyl ether, acetone,tetrahydrofuran, benzene, toluene, glacial acetic acid, and a mixturesolvent of them, but is not limited to these. The said organicnon-solvent is methanol, ethanol, propanol, isopropanol, petroleumether, alkane, paraffine, and a mixture solvent thereof, but is notlimited to these.

When the organic phase is prepared, the content of the pharmaceuticallyacceptable accessories in the organic solvent is not limited if theseaccessories can be dissolved in the organic solvent, but in a view ofthe balance between the possible concentration and the reduction oforganic solvent, the concentration is preferably 1-30%(w/v).

As comparing the solvent-volatilizing method and the spray-drying methodfor the preparation of microspheres, in view of the particlehomogeneousness and the simple operation, the spray-drying method ispreferred, while in view of the reduction of initial release, thesolvent-volatilizing method is preferred.

After the microspheres of dopamine receptor agonist of the presentinvention are formed, they may be subjected to particle grading or notif particle size is sufficiently homogeneous, washing, drying andsubpackage according to prescribed dosage, and then they may beprocessed to form injectable powder from which an injection can beprepared in situ. The injectable powder may be prepared directly fromthe said microspheres from which an injection solution can be preparedin situ by mixing and suspending with physiological saline; or themicrospheres are mixed with prescribed amounts of isotonic salt,mannitol, glucose, etc., and an injection solution can be prepared insitu by adding an prescribed amount of injectable pure water; or themicrospheres of an injection amount are suspended and then freeze-driedin advance, and water is added before using. In the present invention,the method for treatment of diseases associated with dopamine receptorand the method for treatment of Parkinson Disease are carried out bygiving patients needing the above treatments the injection solution ofdopamine receptor agonist of the present invention. Any administrationmethod of using injection can be used, for example, intramuscularinjection, subcutaneous injection, intradermal injection, intraabdominalinjection, etc. In view of ease administration, intramuscular injectionand subcutaneous injection are preferred.

The administration dosage of the sustained-release microspheres ofdopamine receptor agonist of the present invention, taking rotigotine asexample, is 10-400 mg of rotigotine per injection for a patient having abody weight of 60 kg, and the injection volume is 1-5 ml, preferably 1-3ml. The injection administration interval is at least one week or twoweeks. Specific conditions are properly adjusted according to patient'sage, body weight and conditions.

The administration interval of the sustained-release microspheres ofdopamine receptor agonist of the present invention is at least one week,preferably at least two weeks, more preferably at least 20 days, evenmore than 2 months. Thus, the life quality of patients with ParkinsonDisease is improved, and the problem of daily administration isovercome.

The long-acting sustained-release microspheres of the present inventionhave a high encapsulation rate, a continuous and stable drug release, astable and effective blood drug level in patient's body, bettertherapeutic effects and low side-effects, and thus overcome thedrawbacks of conventional dosage forms and can bring about goodtherapeutic effects in treatment of Parkinson Disease.

1. Implants

The active components and pharmaceutically acceptable polymeraccessories used in the implants of the present invention areessentially similar with those of the above sustained-releasemicrospheres, so that only their differences are illustrated as follows.

According to the above statements, since the implants are embeddedtopically, proviso that a proper release is ensured, the content ofactive component can be at a relatively high level, but appropriatelynot more than 50%.

The implants of the present invention can be prepared according toconventional methods in the art, preferably by the following method:dissolving the dopamine receptor agonist in an organic solvent,sufficiently and homogeneously mixing with a pharmaceutically acceptablepolymer accessories, heating and extruding to form rod-shape implants,wherein the organic solvent is methanol, ethanol, isopropanol, ethylether, butyl ether, methyl ethyl ether, methyl butyl ether, hexane,heptane, octane, or a mixture thereof, but is not limited to these.

The implants of the present invention can be embedded subcutaneously byconventional operation or injection in clinic, and drug disperses fromthe implants into blood slowly and enters into circulation system. Theadministration interval of the implants of the present invention is atleast one month, even 4-6 months, which greatly facilitates theadministration for patients with Parkinson Disease.

2. Injectable Gels

The active components and pharmaceutically acceptable polymeraccessories used in the injectable gels of the present invention areessentially similar with those of the above sustained-releasemicrospheres, so that only their differences are illustrated as follows.

According to the above statements, since the injectable gels formtopical implants after they are injected in body, proviso that theactive component can be dissolved into an organic solvent and a properrelease is ensured, the content of the active component can be at arelatively high level, but appropriately not more than 50%.

The injectable gels of the present invention can be prepared accordingto conventional methods in the art, preferably by the following method:weighing dopamine receptor agonist and pharmaceutically acceptablepolymer accessories, dissolving them into an organic solvent to obtainan injectable gel. The solvent is a pharmaceutically acceptable organicsolvent such as N-methyl pyrrolidone, DMSO, etc., but is not limited tothese two solvents. In clinic, the injectable gel of the presentinvention can be directly injected subcutaneously or intramuscularly,then the organic solvent quickly diffuses into body liquid and ismetabolized, the gel is solidified subcutaneously or intramuscularly toform an implant, and the drug gradually diffuses from the implant intocirculation system in vivo. The administration interval of theinjectable gels of the present invention is at least two weeks. Thus,the injectable gels of the present invention are ease for administrationand overcome the drawbacks of conventional oral dosage forms.

EXAMPLES

The long-acting sustained-release dosage forms of dopamine receptoragonist of the present invention are further illustrated by thefollowing examples and experiments, but these examples are not intendedto limit the present invention.

In the following examples, the diameters of microspheres were measuredby L2000 type automatic laser particle size meter (Beckman Coulter) thatwas well known in the art. The concentrations were measured by highperformance liquid chromatograph (HPLC) according to methods asdisclosed in documents, such as Journal of Modern Applicable Pharmacy,1993, 10(1), pages 51-52, and Journal of Chinese Medical andPharmaceutical Industry, 1999, 30(8), pages 363-365, etc.

Example 1

0.1 g of rotigotine and 0.9 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=25,000) were dissolved in 5ml dichloromethane, and then are added dropwise into 250 ml of 0.5% PVAwater solution under vigorous agitation (1200-1600 rpm), the vigorousagitation was continued from 3-10 min after the addition was completed,then the agitation rate was reduced to 300 rpm, the solvent wasvolatilized for 4-6 hours, and microspheres was filtered and washed withdistilled water for three times, and freeze-dried. According to themeasurement of laser particle size meter, the microspheres had aparticle diameter of 1-250 micrometers and a particle diameterdistribution as shown in FIG. 2. The scanning electron microscope photoof the microspheres obtained in Example 1 is shown in FIG. 3.

Example 2

Microspheres having 10% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.1 g of rotigotine and 0.9 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=13,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 3

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine and 0.8 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=25,000), wherein 250 ml of0.5% sodium carboxymethylcellulose water solution was used to replacethe 0.5% PVA water solution. The microspheres passed a screen to removemicrospheres having a particle diameter of greater than 150 micrometer,and subpackaged.

Example 4

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine and 0.8 g of poly(lactide-glycolide)(lactide:glycolide=75:25, molecular weight=11,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 5

0.1 g of rotigotine and 0.9 g of poly(lactide-glycolide)(lactide:glycolide 50:50, molecular weight=25,000) were weighed anddissolved by adding 10 ml dichloromethane under stirring, then atomizedinto 200 ml petroleum ether by a conventional atomizing method,extracted and filtered, and dried to obtain microspheres. Themicrospheres had a particle diameter of 1-100 micrometers according tomeasurement, and then subpackaged.

Example 7

Microspheres having 10% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.1 g of rotigotine and 0.9 g of polycaprolactone (molecularweight=45,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 150 micrometer, andsubpackaged.

Example 8

Microspheres having 15% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.15 g of rotigotine and 0.85 g of polylactic acid) (molecularweight=12,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 150 micrometer, andsubpackaged.

Example 9

Microspheres having 15% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.15 g of rotigotine and 0.85 g of poly(lactide-glycolide)(lactide:glycolide 50:50, molecular weight=40,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 10

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine formate and 0.8 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight 25,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 11

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine acetate and 0.8 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=25,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 12

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine propionate and 0.8 g of poly(lactide-glycolide)(lactide:glycolide 50:50, molecular weight=25,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 13

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine benzoate and 0.8 g of poly(lactide-glycolide)(lactide:glycoiide 50:50, molecular weight=25,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 14

Microspheres having 20% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.2 g of rotigotine benzoate and 0.8 g of poly(lactide-glycolide)(lactide:glycolide 50:50, molecular weight=40,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 15

Microspheres having 15% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.15 g of ropinirole and 0.85 g of poly(lactide-glycolide)(lactide:glycolide 50:50, molecular weight=25,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 16

0.15 g of ropinirole hydrochloride was ground to have an averageparticle size of less than 1 micrometer, 0.85 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=25,000) was dispersed in 5 ml dichloromethane, and the method ofExample 1 was employed to prepare microspheres having 15% drug and aparticle diameter of 1-250 micrometers. The microspheres passed a screento remove microspheres having a particle diameter of greater than 150micrometer, and subpackaged.

Example 17

Microspheres having 15% drug and a particle diameter of 1-250micrometers were prepared according to the method of Example 1 by using0.15 g of pramipexole and 0.85 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=25,000). The microspherespassed a screen to remove microspheres having a particle diameter ofgreater than 150 micrometer, and subpackaged.

Example 18

0.15 g of pergolide methanesulfonate was ground to have an averageparticle size of less than 1 micrometer, 0.85 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=25,000) was dispersed in 5 ml dichloromethane, and the method ofExample 1 was employed to prepare microspheres having 15% drug and aparticle diameter of 1-250 micrometers. The microspheres passed a screento remove microspheres having a particle diameter of greater than 150micrometer, and subpackaged.

Example 19

0.15 g of terguride maleate was ground to have an average particle sizeof less than 1 micrometer, 0.85 g of poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=25,000) was dispersed in 5 mldichloromethane, and the method of Example 1 was employed to preparemicrospheres having 15% drug and a particle diameter of 1-250micrometers. The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 150 micrometer, andsubpackaged.

Example 20

1 g of rotigotine was dissolved in 1 ml dichloromethane, andsufficiently mixed with 9 g ground polyanhydride(poly(1,3-dicarboxyphenoxypropane-sebacic acid), molecular weight40,000, average particle diameter about 200 micrometers), then heatedand extruded to prepare a rod-shape implant having 10% drug, a diameterof 1 mm and a length of 30 mm.

Example 21

1 g of dinapsoline hydrobromide was dissolved in 1 ml dichloromethane,and sufficiently mixed with 9 g ground polyanhydride(poly(1,3-dicarboxy-phenoxypropane-sebacic acid), molecularweight=40,000, average particle diameter=about 200 micrometers), thenheated and extruded to prepare a rod-shape implant having 10% drug, adiameter of 1 mm and a length of 30 mm.

Example 22

0.15 g rotigotine and 0.85 g poly(lactide-glycolide)(lactide:glycolide=50:50, molecular weight=25,000) were weighed anddissolved in N-methyl pyrrolidone to prepare an injectable gel having adrug load of 15% (where solvent was not taken into account).

Example 23

0.15 g cabergoline diphosphate and 0.85 g poly(lactide-glycolide)(lactide:glycolide 60:40, molecular weight=25,000) were weighed anddissolved in N-methyl pyrrolidone to prepare an injectable gel having adrug load of 15% (where solvent was not taken into account).

Experiment 1: In Vitro Release Test (1) of Rotigotine Microspheres

The microspheres of Examples 1 to 6 were used in the release test thatstimulated the in vivo conditions.

According to the inventors' studying, the drug release behavior in abuffer having a pH value of 7.4 (sodium phosphate buffer) was similarwith that in body, so that the in vivo release mode was simulated byusing the buffer although it was different from the in vivo environment(see also Experiment 3 and FIG. 13).

Experimental Instrument:

thermostatic shaker, centrifugal machine.

Experimental Conditions:

temperature 37±0.5° C., rotation speed=30 rpm.

Experimental Methods:

precisely weighing about 1 mg of sample, placing in a 5 ml plasticcentrifugal tube with lid, adding 5 ml of release medium (pH=7A, sodiumphosphate buffer), keeping at a temperature and a rotation speed in athermostatic shaker, and sampling according to the schedule.

Sampling methods: centrifuging the centrifugal tube under 3600 rpm for20 minutes, precisely taking 3 ml solution and supplementing 3 ml ofrelease medium at the same time, and detecting the obtained solution byHPLC.

Sampling time (day): 0, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 24,26, 28 and 30 (different microspheres have different sampling time),wherein the 0^(th) day represents the drug concentration before theadministration on the day when the drug is administrated.

The in vitro release effects of the microspheres of Examples 1-6 undercondition of pH7.4 are separately shown in FIGS. 4-9. The experimentalresults of the microspheres obtained in Examples 1-6 are shown in Table1.

TABLE 1 Drug content Method for Release percentage (%) Sample No.(μg/mg) obtaining value 0 1 2 4 6 8 10 12 14 Example 1 100 That day 05.8 1.6 1.2 2.0 3.2 3.7 3.4 3.8 Cumulative 0 5.8 7.4 9.8 13.8 20.2 27.634.5 42.1 Example 2 100 That day 0 11.5 11.2 6.1 6.5 5.7 5.1 4.7 3.5Cumulative 0 11.5 22.7 35.0 48.1 59.5 69.7 79.1 86.1 Example 3 200 Thatday 0 3.7 5.7 11.4 11.1 7.3 5.1 4.3 3.0 Cumulative 0 3.7 9.4 32.2 54.469.0 79.2 88.0 94.0 Example 4 200 That day 0 13.1 1.5 6.1 5.6 3.9 3.53.4 2.6 Cumulative 0 13.1 14.6 26.9 38.0 45.7 52.8 59.5 64.7 Example 5100 That day 0 34.0 8.0 4.0 5.0 4.5 4.3 4.0 3.5 Cumulative 0 34.0 42.050.0 60.0 69.0 77.5 85.5 92.4 Example 6 100 That day 0 44.8 11.9 6.5 4.03.0 2.9 □ 1.7 Cumulative 0 44.8 56.7 70.7 78.7 84.7 90.5 □ 97.2 DrugMethod for content obtaining Release percentage (%) Sample No. (μg/mg)value 16 18 20 22 24 26 28 30 Example 1 100 That day 2.7 3.1  3.5 3.5 4.2 3.6  3.1 1.9 Cumulative 47.5 53.6 58.8 65.8 72.7 81.0 94.3 98.0Example 2 100 That day □ 1.8 □ 1.5 Cumulative □ 93.3 □ 99.3 Example 3200 That day 1.7 Cumulative 97.4 Example 4 200 That day □ 1.5 □ 1.8 □2.3 □ 1.7 Cumulative □ 70.9 □ 78.2 □ 87.4 □ 94.2 Example 5 100 That day□ 1.8 □ 1.0 Cumulative □ 95.8 □ 100 Example 6 100 That day □ 0.65Cumulative □ 99.8Note: the release on that day in the table is calculated from thecumulative release until that day; concretely, it is assumed that thedrug release rate during the period between the two measurements isunchanged. As expressed by a formula, the release on that day=(thecumulative release on that day−the cumulative release obtained by theprevious measurement)÷the number of days between the day for theprevious measurement and that day.

Taking Example 1 as example, the release on the 0^(th) day is 0, thecumulative release on the 1^(st) day is 5.8, so that the release on the1^(st) day=(5.8−0)÷(1−0)=5.8; the release on the 2^(nd) day is 7.4, sothat the release on the 2^(nd) day=(7.4−5.8)÷(2−1)=1.6; and the releaseon the 4^(th) day is 9.8, so that the release on the 4^(th)day=(9.8−7.4)÷(4−2)=1.2. The rest may be deduced by analogy.

According to the table, the sustained-release microspheres of rotigotineof the present invention has a stable release within the period of morethan two weeks. Thus, the administration frequency for patients withParkinson Disease can be reduced significantly, the dosage can beeffectively controlled, and side-effects are avoided.

Experiment 2: In Vitro Release Test 2 of Rotigotine Microspheres

The microspheres of Examples 11 and 13 were measured according to thesame method of Experiment 2, except that the sampling time (day) was: 0,1, 2, 4, 6, 8, 12, 14, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36 and 38.

The in vitro release effects of the microspheres of Examples 11 and 13under condition of pH7.4 are separately shown in FIGS. 10 and 11.

Experiment 3: In Vivo Release Test of Sustained-Release MicrospheresAnalysis of Plasma Samples

Pretreatment of plasma samples: precisely taking 500 μL of plasma sampleand placing it in a test tube, adding 100 mL of an internal standardsolution (1 ng/mL benadryl methanol-water (50:50, v/v) solution), adding1004 methanol-water (50:50, v/v) and 100 μL 1M Na₂CO₃ solution, andmixing homogeneously; adding 3 mL, n-hexane-dichloromethane-isopropanol(300:150:15, v/v/v), mixing at eddy current state for 1 minute,reciprocally shaking for 15 minutes (240/min), centrifuging for 5minutes (3500 rpm), transferring the organic phase as upper layer intoanother test tube, blowing nitrogen gas and drying at 25° C., dissolvingthe residue by adding 1004 mobile phase, mixing under eddy currentstate, and taking 204, for LC/MS/MS analysis.

Chromatography Conditions: chromatography column: Zorbax Extend-C₁₈column, 5 μm of particle diameter, 150×4.6 mm I.D. (Agilent Company,U.S.A.); mobile phase: acetonitrile-water-formic acid (300:300:6,v/v/v); flow rate: 0.7 mL/min; column temperature: 37° C.; sample size:20 L.

Mass spectrum conditions: ion source: ion-spray ionizing source;ion-spray voltage: 5000V; temperature: 450° C.; internal source gas 1(GS 1, N₂) pressure: 50 psi; gas 2 (GS2, N₂) pressure: 50 psi;gas-curtain gas (N₂) pressure: 15 psi; positive ion detection mode;scanning mode: multiple reaction monitoring (MRM); DP voltage: 56V;impact gas (N₂) pressure: 3 psi; the ion reactions for quantitativeanalysis are separately m/z 317.1→m/z 147.1(MD102) and m/z 256.1→m/z167.1 (benadryl).

Preparation of working curve: taking 0.5 mL blank plasma, adding 100 μLof MD 102 standard serial solution, preparing plasma samplescorresponding to plasma concentrations of 0.01, 0.03, 0.10, 0.30, L00and 2.00 ng/mL; and preparing standard curve according to the “Methodsfor analysis of plasma sample” of Section 11 of the Pharmacopoeia ofPeople's Republic of China, Edition 2000. The linear regression equationas the standard curve is obtained by using the concentration of thesubstance to be tested in plasma as abscissa, the peak area ratio of thesubstance to be test to the internal standard as ordinate, andconducting regression calculation by using a weighted least squaremethod (W=1/x²).

Experimental Method:

3 Healthy beagles, one female and two males, having a body weight of9-11 kg, feeding and drinking water ad libitum, were intramuscularlyadministrated with rotigotine in a dosage of 5.5 mg/kg, and 3 mL bloodsample was taken from anterior limb vein according to the prescribedschedule after the administration, placed in heparinized test tube, andcentrifuged under 6000 rpm for 10 min, then the plasma was separated andpreserved at −20° C., and analyzed according to the above analysismethods.

FIG. 12 is the polygonal diagram of blood rotigotine concentrationchange in vivo test (beagle) for the microspheres obtained in Example 3.

FIG. 13 is the diagram of comparison between the polygonal diagram ofdaily or accumulative release rate in pH7.4 simulative release liquidand the polygonal diagram of blood rotigotine concentration change invivo test (beagle) for the sustained-release microspheres obtained inExample 3.

According to FIG. 12, it can be seen that the drug release of themicrospheres of the present invention is stable for at least two weeks.

Experiment 4: In Vitro Release Test of Implants Experimental Method:

Experimental Instrument:

thermostatic shaker, centrifugal machine.

Experimental Conditions:

temperature 37±0.5° C., rotation speed=30 rpm.

Experimental Methods:

precisely weighing about 0.1 g of the implant of Example 20, placing ina 5 ml plastic centrifugal tube with lid, adding 5 ml of release medium(pH-7.4, sodium phosphate buffer), keeping at a temperature and arotation speed in a thermostatic shaker, sampling 3 ml according to theschedule and supplementing 3 ml of the release medium.

Sampling time (day): 0, 1, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77,94, 91, 98 and 105, wherein the 0^(th) day represents the drugconcentration before the administration on the day when the drug isadministrated. The results are shown in Table 2.

TABLE 2 Sample Method for Release percentage (%) No. obtaining value 0 17 14 21 28 5 42 49 Example That day 0 1.2 0.84 0.72 0.81 0.75 0.94 1.82.2 20 Cumulative 0 1.2 6.24 11.28 16.95 22.2 28.78 41.38 57.23 Methodfor Release percentage (%) obtaining value 56 63 70 77 84 91 98 105 Thatday 1.72 0.91 0.72 0.62 0.48 0.32 0.25 0.22 Cumulative 69.27 75.64 80.6885.02 88.38 90.62 92.37 93.31

According to the results of above experiment, the implant of the presentinvention can continuously release drug for more than two months.Experiment 5: In vitro release test of injectable gel

Experimental Method:

Experimental Instrument:

thermostatic shaker, centrifugal machine.

Experimental Conditions:

temperature=37±0.5° C., rotation speed=30 rpm. Experimental methods:precisely weighing about 0.1 mL of the injectable gel obtained inExample 22, placing in a 5 ml plastic centrifugal tube with lid, adding5 ml of release medium (pH=7.4, sodium phosphate buffer), keeping at atemperature and a rotation speed in a thermostatic shaker, sampling 3 mlaccording to the schedule and supplementing 3 ml of the release medium.

Sampling time (day): 0, 1, 2, 5, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34,38, 42, 45, wherein the 0^(th) day represents the drug concentrationbefore the administration on the day when the drug is administrated. Theresults are shown in Table 3.

TABLE 3 Method for Release percentage (%) Sample No. obtaining value 0 12 5 7 10 13 16 19 Example 22 That day 0 8.2 2.6 2.2 2.1 2.2 2.1 2.5 2.8Cumulative 0 8.2 10.8 17.4 21.6 28.2 34.8 42.3 50.7 Method for Releasepercentage (%) obtaining value 22 25 28 31 34 38 42 45 That day 2.7 2.22.1 1.5 1.2 1.6 1.4 1.2 cumulative 58.8 65.4 71.7 76.2 79.8 86.2 91.895.4According to the results of the above experiment, the gel of the presentinvention can continuously release drug for more than 45 days.

Example 24

Microspheres having 8% drug (actually having 7.8% drug) and a particlediameter of 1-250 micrometers were prepared according to the method ofExample 1 by using 0.08 g of rotigotine and 0.92 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=25,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 180 micrometer, andsubpackaged.

The in vitro release effect of the rotigotine microspheres (actuallyhaving 7.8% thug) under condition of pH7.4 is shown in FIG. 16.

The sustained-release microspheres were administrated to beagle for invivo release test, wherein the dosage of rotigotine was 2.75 mg/kg (byassuming the body weight of beagle as 10 kg, the dosage corresponds to1150 mg microspheres having 7.8% drug that is injected one time to anadult human being having a body weight of 65 kg). The microspheres weresuspended in physiological saline and administrated intramuscularly, andblood samples were taken between 1 and 30 days and detected by HPLC-MSassay to indicate a blood drug level of 0.05-0.4 ng/ml. This proves thatthe sustained-release microspheres can stably release drug for at least30 days, although the blood drug concentration is relatively lower andcan hardly meet the requirement of blood drug concentration (>0.5 ng/mL)for treatment of Parkinson Disease of patients, especially those inevaluation period, while the increase of dosage means overdose injectionthat may lead to complaint and suffering in patients.

FIG. 17 is the polygonal diagram of blood rotigotine concentrationchange in vivo test (beagle) for the rotigotine microspheres (actuallyhaving 7.8% drug) obtained in Example 24.

Example 25

Microspheres having 30% drug (actually having 26.5% drug) and a particlediameter of 1-250 micrometers were prepared according to the method ofExample 1 by using 0.30 g of rotigotine and 0.70 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=45,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 200 micrometer, andsubpackaged.

The in vitro release effect of the rotigotine microspheres (actuallyhaving 26.5% drug) under condition of pH7.4 is shown in FIG. 18.

Example 26

Microspheres having 40% drug (actually having 34% drug) and a particlediameter of 1-250 micrometers were prepared according to the method ofExample 1 by using 0.4 g of rotigotine and 0.6 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=45,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 200 micrometer, andsubpackaged.

The in vitro release effect of the rotigotine microspheres (actuallyhaving 34% drug) under condition of pH7.4 is shown in FIG. 19.

The sustained-release microspheres were administrated to beagle for invivo release test, wherein the dosage of rotigotine was 5.5 mg/kg (byassuming the body weight of beagle as 10 kg, the dosage corresponds to520 mg microspheres having 34% drug that is injected one time to anadult human being having a body weight of 65 kg). The microspheres weresuspended in physiological saline and administrated intramuscularly, andblood samples were taken between 1 and 11 days and detected by HPLC-MSassay to indicate a blood drug level of 28-0.05 ng/ml. The results showthat when the drug load is relatively higher (>30%), the initial releaseof microspheres within 24 hours is relatively high, which results in theside-effects such as intensive emesis and so on in animal, the blooddrug level decreases quickly with the increase of time, and thesustained-release effects are not good.

FIG. 20 is the polygonal diagram of blood rotigotine concentrationchange in vivo test (beagle) for the rotigotine microspheres (actuallyhaving 34% drug) obtained in Example 26.

Example 27

Microspheres having 50% drug (actually having 41% drug) and a particlediameter of 1-250 micrometers were prepared according to the method ofExample 1 by using 0.50 g of rotigotine and 0.50 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=45,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 200 micrometer, andsubpackaged.

The in vitro release effect of the rotigotine microspheres (actuallyhaving 41% drug) under condition of pH7.4 is shown in FIG. 21.

Example 28

Microspheres having 50% drug (actually having 43% drug) and a particlediameter of 1-250 micrometers were prepared according to the method ofExample 1 by using 0.50 g of rotigotine and 0.50 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecularweight=35,000). The microspheres passed a screen to remove microsphereshaving a particle diameter of greater than 200 micrometer, andsubpackaged.

The in vitro release effect of the rotigotine microspheres (actuallyhaving 43% drug) under condition of pH7.4 is shown in FIG. 22.

Example 29

Microspheres having 60% drug (actually having 47% drug) and a particlediameter of 1-250 micrometers were prepared according to the method ofExample 1 by using 0.60 g of rotigotine and 0.40 g ofpoly(lactide-glycolide) (lactide:glycolide=50:50, molecular weight45,000). The microspheres passed a screen to remove microspheres havinga particle diameter of greater than 200 micrometer, and subpackaged.

The in vitro release effect of the rotigotine microspheres (actuallyhaving 47% drug) under condition of pH7.4 is shown in FIG. 23.

INDUSTRIAL PRACTICAL APPLICABILITY

The present invention employs biodegradable polymer to embed dopaminereceptor agonist in order to prepare long-acting sustained-releasedosage forms, such as injectable microspheres, injectable gels andimplants, which have an administration interval of more than two weeks,in particular, the implants have an administration interval of more thanone month, so that the present invention greatly facilitates theadministration for patients having Parkinson Disease and other dopaminereceptor-associated diseases.

1. A method of treating Parkinson disease in a patient in need thereofcomprising administering to the patient a long-acting sustained releaseformulation comprising: (1) rotigotine or a pharmaceutically acceptablesalt thereof; and (2) poly(lactide-glycolide), wherein rotigotine or apharmaceutically acceptable salt thereof is present in thesustained-release formulation at 10-30% by weight, andpoly(lactide-glycolide) is present in the sustained-release formulationat 70-90% by weight, and wherein the rotigotine or a pharmaceuticallyacceptable salt thereof and poly(lactide-glycolide) form a solidsolution.
 2. The method of claim 1 wherein administering comprisesinjecting the long-acting sustained-release formulation as microspheresor a gel.
 3. The method of claim 1 wherein administering comprisessubcutaneously implanting the long-acting sustained-release formulation.4. The method of claim 1 wherein said poly(lactide-glycolide) has amolecular weight of 5,000-100,000 daltons.
 5. The method of claim 4,wherein the polymerization ratio of lactide to glycolide in thepoly(lactide-glycolide) is between 95:5 and 5:95.
 6. The method of claim4 wherein the polymerization ratio of lactide to glycolide in thepoly(lactide-glycolide) is between 75:25 and 25:75.
 7. The method ofclaim 2 wherein the long-acting sustained-release formulation is aninjectable composition of sustained-release microspheres, themicrospheres having particle, diameters of 50 to 200 microns.
 8. Themethod of claim 1 wherein the pharmaceutically acceptable salt ofrotigotine is a salt formed between the active ingredient and aninorganic acid, an organic, acid or an acidic amino acid.
 9. The methodof claim 8 wherein the inorganic acid is hydrochloric acid, sulfuricacid, phosphoric acid or nitric acid; the organic acid is citric, acid,fumaric acid, maleic acid, acetic acid, benzoic acid, methane sulfonicacid, naphthalene sulfonic acid, or p-toluene sulfonic acid; and theacidic amino acid is glutamic acid or aspartic acid.
 10. The method ofclaim 1 wherein said rotigotine or pharmaceutically acceptable salt isrotigotine, rotigotine formate, rotigotine acetate, rotigotine benzoate,rotigotine butyrate, rotigotine iso-butyrate or a hydrochloride thereof.